Some people say that the Marathon de Sables — a six-day, 155-mile (249-kilometer) run through the Sahara Desert — is the toughest athletic event on Earth. That's because not only do you have to run as fast as possible while enduring brutal heat and the glare of the sun, but there's also the danger of getting lost in one of the most inhospitable places on the planet.

In 1994, a 39-year-old Italian pentathlete named Mauro Prosperi discovered just how dangerous this race is. After he was forced by an eight-hour sandstorm to take shelter for the night, he awakened the next morning to discover that he was lost in the desert, and only had half a bottle of water left. He resorted to drinking his own urine.

Two days in, he stumbled into an abandoned Muslim shrine where he noticed some bats huddled together. Prosperi grabbed a handful of them, cut off their heads with a knife, and then sucked out their insides to drink their blood and quench his thirst. Eventually, he did his vampire act on 20 bats. When another three days passed with no sign of rescue, he slit his wrists and waited to die, but his blood had thickened due to dehydration so it wouldn't drain out.

Prosperi took this as a sign that he should keep living, left the shrine and began walking across the desert. On day eight, he discovered an oasis and got to drink some water at last. The next morning, he saw some shepherds, who summoned rescuers [source: Prosperi].